Plural fluorescent lamp starting circuit using an unignited lamp as ballast



Apnlv 18, 1967 SHU NGO FURUI 3,315,123

PLURAL FLUORESCENT LAMP STARTING CIRCUIT USING AN UNIGNITED LAMP ASBALLAST Filed Jan. 11, 1965 i. Y m s 15' Z B/METALL/G GLOW J'MBTEE:SWITCH j v VEN TOR HTMRNE Y5 to provide improved means and UnitedStates Patent Oihce 3,315,123 PLURAL FLUORESCENT LAMP STARTING CIRCUITUSING AN UNHGNHTED LAMP AS BALLAST Shungo Furni, Yokohama, Japan,assignor of fifty percent to Grace Thunberg, Garden Grove, Calif. Filed.lan. 11, 1965, Ser. No. 424,718 Claims priority, application Japan,Jan. 18, 1964, $9/13,5llfi 8 Claims. (Cl. 315-190) The present inventionrelates to a highly eificient and economical circuit arrangement andtechniques useful in fluorescent lamp lighting systems.

In brief, the arrangements described herein comprise two fluorescentlighting lamps which are lit in sequence during the starting operationusing a simple but new circuitry. Using this new circuitry involving arelatively high resistance (or a relatively high impedance electricconductor) across one of the lamps and the connection of a glow starterswitch across each of said lamps, peculiar advantages and improvedresults are obtained. These advantages and improvements make it possibleto operate fluorescent lamps much more economically not only from theviewpoint of initial cost of ballast fabrication, but also in moreefficient use of electrical wattage during the hours of the lampoperation.

It is therefore a general object of the present invention technical artswhereby the above-mentioned advantages and results may be obtained.

A specific object of the present invention is to provide circuitarrangements and techniques whereby the mag nitude of the startingvoltage may be relatively small, thereby lessening the voltagerequirements of the equipment and also lessening the voltage required tobe attenuated during the lit condition of the lamps.

Another specific object of the present invention is to provide improvedcircuit arrangement and techniques of this character whereby allstarting voltage applied, may be utilized for lighting the lamps withoutalmost any voltage attenuation, if desired.

Another specific object of the present invention is to provide improvedcircuit arrangements and techniques of this character whereby relativelysmall amount of power is required to be dissipated in a ballast element.

Another specific object of the present invention is to provide improvedcircuit arrangements and techniques of this character involving the useof two gaseous electric discharge lamps wherein during the startingoperation essentially one of the lamps acts as a ballast for the otherlamp, with the lamps being sequentially lit.

Another specific object of the present invention is to provide improvedcircuit arrangements and techniques for lessening electrical powercharge per lamp for con snmers.

Another specific object of the present invention is to provide improvedcircuit arrangements and techniques of this character whereby the use ofrelatively low starting voltage per lamp makes it possible to prevent adangerous excessive current flow through the lamps and ballast elementin case a series capacitor is short-circuited due to malfunctioningthereof.

Another specific object of the present invention is to provide a systemof this character using two glow starter switches in series andrelatively low ballast voltage per lamp, whereby the malfunctioning ofassociated glow starter switches does not result in flow of excessivecurrent, when, for example, the contact point of one of them becomesstuck in a circuit closing condition or position.

Another specific object of the present invention is to provide a systemof this character in which automatic 3,3l5,l23 Patented Apr. 18, 1967voltage regulation is obtained by coaction of a series capacitor,characteristics of a transformer and the lamp inductance.

Another specific object of the present invention is to provide a systemof this character wherein the ballast components may be made relativelysmall in size, of relatively light weight, and with relatively smallexpense.

Another specific object of the present invention is to provide a systemof this character in which the applied no-load secondary voltage of theballast transformer may be used for dual functions: that is, to use theapplied voltage for the lamp as the ballast voltage required forstarting another lamp, and to use such applied voltage as the lightingvoltage for itself.

Another specific object of the present invention is to provide improvedcircuit arrangements and techniques of this character whereby all theno-load secondary voltage of the ballast transformer may be applied andutilized for lighting the lamps without any voltage attenuation, ifdesired; that is, to eliminate a separate source of ballast voltage forstarting and lighting the lamps.

Another specific object of the present invention is to provide a systemof this character in which a good power factor, a good voltagecharacteristics, and a good performance may be obtained.

Still another specific object of the present invention is to provide asystem of this character whereby said above mentioned objects may beapplied to circuit arrangement of this character in which a number ofthe lamps are connected in series.

While the present invention is described specifically in connection withflorescent lamps, it will be understood that the invention in itsbroader aspect is applicable also to the control of other devices whichexhibit a so-called negative resistance characteristic.

The features of the present invention which to be novel are set forthwith particularity in the appended claims. This invention itself, bothas to its organization and manner of performance, together with furtherobjects and advantages! thereof, may be best understood by reference tothe following drawing, in which the figure illustrates a form of thepresent invention.

Referring to the figure, the same includes two fluorescent lamps 4 and5, the lamp 4 having cathode filaments 4A, 4B at the opposite endsthereof; and likewise, cathode filaments 5A, 5B are at the opposite endsof theother lamp 5.

The filament 4A is connected to opposite terminals of a transformerwinding 1A. The filaments 4A, 4B, 5A and 5B are connected in series withglow starter switches 6 and 7. A terminal 15 of coil 1B is connectedthrough a capacitor 2 to one terminal of filament 5B, and the aforesaidcapacitor 2 being shunted by a resistance 3, and the aforesaid glowstarter switch 6 being shunted by a capacitor 9, and glow starter switch7 being shunted by a capictor '10. The high resistance (or a highimpedance electric conductor) 8 is connected in shunt with the lamp 4,consequently with glow starter switch 6 too, and in series with glowstarter switch 7.

It will be seen from this circuit arrangement that an autotransformer isprovided in which the primary winding is essentially that winding 1Abetween the terminals 13 and 14, and the secondary winding isessentially that winding 13 between terminals 13 and 15. All of thewindings 1A and 1B are wound on the same core.

The glow starter switches 6 and 7 are both normally open type switchbetween contacts of which a gaseous discharge maybe produced with theresulting heating of one of the contacts, of bimetal, causing it to warpand engage the contact to thereby close the switch. When the switch isthus closed by the heat initially produced by the gaseous dischargebetween these contacts, the biare believed 3 metal element is thenallowed to cool and in so doing returns to its initial condition and inso doing opens the switch 6 or 7. Such glow starter switches 6 and 7 perse form no part of the present invention and indeed are well known inthe art and may, for example, be constructed as described in the U.S.Patent 2,680,211 of J. H. Campbell, patented June 1, 1954, and assignedon its face to General Electric Company. Such glow type starter switchesmay, as described in such Patent 2,680,211, comprise a glass envelopecontaining an ioni'z'able gas such as neon and including therein a pairof electrodes consisting of a curved bimetallic strip and operative suchthat in its normal condition, there is no contact between electrodes butwhen, however, a sufficient voltageis developed across the electrodes, adischarge occurs whichproduces heat to heat up the electrodes and causethe bimetal to move the switch contacts into engagement whereupon theswitch closes and the glow ceases. When the glow thus ceases, thebimetal is allowed to cool and when it cools sufliciently the switchcontacts are returned by the cooled bimetal to their initial opencondition.

In the operation of the circuit arrangement shown in FIG. 1, when theswitch 12 is closed, the transformer 1 is energized and the no-loadsecondary or starting voltage is impressed on the glow starter switch 7by means of the high resistance resistor 8. Thereupon a gaseousdischarge takes place between the contacts of glow starter switch 7 andthe bimetal element of the switch begins to warp so as to move towardscircuit closing position. When the switch 7 is closed, the appliedstarting voltage is transferred to glow starter switch 6, wherein agaseous dis charge takes place between the contacts of the glow starterswitch 6 and the bimetal element therein begins to warp so as to movetowards circuit closing position. During these movements of said glowstarter switch elements aforesaid, neither one of the two lamps 4 and 5is lit.

However, when the both glow starter switches 7 and 6 close theirswitches, the preheating current may flow through cathode filaments 4A,4B, 5A and 5B of the lamps 4 and 5, heating thereof. Now, as soon as thebimetal contactor of glow starter switch 7 gets cooled and opens itscontact switch, the starting voltage may act in full at both cathodes ofthe lamp 5 to start instantaneously, and as soon as the bimetalcontactor of glow starter switch 6 gets cooled and opens its contactswitch, the starting voltage may act at both cathodes of the lamp 4, tostart it instantly and light normally together with the lamp 5.

Thus in this operation, the lamps 5 and 4 are sequentially lit. When thelamps 5 and 4 are lit, the voltage developed across the same becomessufficiently low enough 'to prevent the production of the gaseousdischarge between the contacts of glow starter switches 7 and 6. Oncethus lit, the lamps 5 and 4 may be extinguished, of course, by openingthe switch 12.

In the system shown in FIG. 1, the starting voltage, i.e., the no-loadsecondary voltage developed across the terminals 13 and 15 is relativelysmall, and may be below 250 volts when the lamps 4 and 5 are of the 40'watt preheated type fluorescent lamps (FL-40) for industrialapplication with enough reserve voltage for the supply line voltagedrop. Typical circuit values are the following: Capacitor 2 may be 4.6microfarads and the capacitors 9 and 10 may be 0.006 microfarad each,which are used essentially for noise suppression. The resistance 3 maybe a value of 1,000,000 ohms, and the high resistance 8 may be 10,000ohms, and the glow starter switches 6 and 7 may be of the FG-4P type.

It will be seen that the foregoing described sequence of events occursbecause of the resistance values in the circuit considering the factthat in the unlit condition, of the lamps 4 and 5 have a high resistanceor impedance. Thus, the resistance 8 of 10,000 ohms assures an initialdischarge between the contacts of the glow starter switch 7 before anyone of the lamps is lit, and when the contacts of switch 7 close, thestarting voltage may be transferred to the glow starter switch 6 toproduce a gaseous discharge therein thereby to heat the bimetalcontactor to warp and close its contact switch. When both glow starterswitches 7 and 6 close their contact switches, it will be apparent thatthe preheating current may flow through cathode filaments of both lamps4 and 5. But in case both glow switches 7 and 6 open their contactswitches exactly simultaneously or at the same time, the startingvoltage is insufficient, thereby neither of these lamps can Start.

On the other hand, when any one of the glow starter switches opensfirst, su'flicient starting voltage acts at both cathodes of the lamp towhich said glow starter switch is connected and such lamps starts itinstantly. Shortly thereafter as soon as the other glow starter switchopens its contact switch, the starting voltage acts at both cathodes ofthe other lamp to which the last-mentioned glow starter switch isconnected, and starts such other lamp immediately following starting ofthe first-mentioned lamp. Thus, either lamp 4 or 5 may be started firstfollowed by the starting of the other lamp depending upon whether switch9 or switch 10 opens first.

In the foregoing example, a starting voltage of 250 volts or 125 voltsper lamp has been used for 40 watt preheated type fluorescent lamps. Butin the present invention, the starting voltage of the same may bereduced to as low as 200 volts, i.e., volts per 40 watt preheated typefluorescent lamp, if desired, in which with a slight increase of thevalue of the series capacitor 2 in order to make a rated lamp current of0.435 ampere to flow at the rated voltage. The starting voltage of 100volts per lamp for 40 watt preheated type fluorescent lamp ispractically equivalent to the terminal lamp voltage under the normallyoperating condition. It means, therefore, in the present invention apossibility of eliminating the use of choke coil ballast thereby toconsume and absorb the ballast voltage after the lamps are lit; or allthe no-load secondary voltage of the ballast transformer may be appliedand utilized for the lamps without any voltage attenuation.

As well-known, all gaseous electric discharge lamps have an inherentcharacteristic of requiring an extra or ballast voltage for startingthem. For example, 200 volts is usually used for starting a 40 wattpreheated type fluorescent lamp (FL-40), although only about 100 voltsis ample enough for lighting it.

Heretofore, in general, the required ballast voltage of the 100 volts istaken from the secondary circuit of the ballast transformer, forexample, in addition, and a choke coil is connected in series with thelamp to absorb the ballast voltage after the lamp is lit, or a leakagetransformer having a secondary voltage of 200 volts is used to reducethe voltage to about 100 volts as soon as the lamp is started and islit. In either case, all of the ballast voltage is consumed and wastedin the choke coil or within the leakage transformer in addition toinvolving the use of expensive ballast and causing much electric lossesand lowering power factor of the circuit.

For example as aforesaid, two 40 watt preheated type fluorescent lamps(FL40) 4 and 5, are connected in series as shown in FIG. 1, with acapacitor 2 in the secondary circuit of the transformer having a no-loadsecondary or starting voltage of 200 volts, thus supplying a lightingvoltage of 100 volts for each lamp. In the system of this circuitarrangement, when starting the lamp 4, the lamp voltage of 100 voltssupplied for the lamp 5 is used instantaneously as the ballast voltagerequired for the lamp 4; and when starting the lamp 5, the lamp voltageof 100 volts supplied for said lamp 4 is used instantly as the ballastvoltage required for starting the said lamp 5; thus making the use ofthe supplied voltage to each lamp for dual purposes, i.e., in course ofstarting as a ballast voltage, and in course of lighting as a lightingvoltage, for those lamps concerned. For this reason, in

the present invention, it requires two or more lamps connected in seriesas shown in FIG. 1, as an example.

Heretofore in general, it was believed that it was absolutely necessaryto use a choke coil ballast or a leakage transformer to provide aballast voltage for operating fluorescent lamps. Using prior artarrangements, only a portion of the supplied volt-ampere power may beutilized for fluorescent lamps, or generally speaking only about 50% ofthe supplied volt-ampere power may be available for the lamps. But inthe present invention, it is possible to utilize even 100% of thesupplied volt-ampere power for fluorescent lamps with a stabilityof thelamp current and good performance practically as the same as theordinary stability and performance, if desired.

When two glow starter switches are used in series as shown in FIG. 2 thevoltage required to operate these glow starter switches will be twicethe voltage required to operate a single glow starter switch inaccordance with the prior art teachings.

But if a high resistance resistor 8 is connected in shunt with the glowstarter switch 6 and in series with the glow starter switch 7, as shownin FIG. 3, it is then possible to operate these series connected twoglow starter switches with a starting voltage equivalent to the startingvoltage to operate a single glow starter switch, i.e., to reduce theformerly required starting voltage to 50%. As shown in FIG. 2, theoperating voltage required becomes twice the voltage required to operatea single switch, as the applied starting voltage is divided between twoof these glow starter switches. But as shown in FIG. 3, the resistance 8is low enough to pass the glow discharge current through to the glowstarter switch 7, but at the same time high enough to sustaintransmitting a voitage high enough to produce the glow discharge at itsbimetal contactor therein, and also high enough to prevent ashort-circuiting condition for the glow starter switch 6. When the glowstarter switch 7 closes its contacts, the same starting voltage may betransferred to the second glow starter switch 6 wherein the single glowstarter switch voltage may produce a gaseous glow discharge at itscontacts thereby heating the bimetal contacts to warp and eventually toclose the switch, thus making it possible two glow starter switchesbeing operated with an operating voltage equivalent to that voltagerequired to operate a single glow starter switch, and to enable theflowing of the preheating current through cathode filaments offluorescent lamps.

While the particular embodiments of the present invention has been shownand described, it will be obvious to those skilled in the art thatchanges and modifications i may be made without departing from thisinvention in its broader aspect and, therefore, the aim in the appendedclaims is to cover all such changes and modifications as fall within thetrue spirit and scope of this invention.

I claim:

1. In a fluorescent lamp circuit arrangement, a first fluorescent lamp;a second fluorescent lamp; each of said lamps having filamentarycathodes; means for heating said cathode filaments; a first glow starterswitch; a second glow starter switch; said first glow starter switchbeing connected in parallel with said first lamp; said second glowstarter switch being connected in parallel with said second lamp; saidglow starter switches being a normally open switch and incorporatingmeans whereby heat from a glow discharge in said glow starter switchcauses said switches to close; a first impedance element connected inparallel with said first lamp; said first lamp being connected in serieswith said second lamp; said first glow starter switch being connected inseries with said second glow starter switch; said first impedanceelement being connected in series with said second glow start r switch;a voltage source; means for energizing said voltage source; a secondimpedance; said voltage source, said second impedance element and saidfirst and second lamps being connected in series circuit; said firstimpedance element being effective to prevent lighting of said secondlamp when said voltage source is initially energized by said energizingmeans with said first impedance element being effective to cause a glowdischarge to appear in said second glow starter switch; said second glowstarter switch being closed by heat produced by glow discharge thereinto connect said voltage source to said first glOW starter switch tocause a giow discharge to appear in said first glow starter switch; whenboth contacts of said second and said first glow starter switches close,said voltage source causes a preheating current flow through saidcathode filaments of said first and second lamps; when said second glowstarter switch opens said voltage source acts at both cathodes of saidsecond lamp to light the same; when said first glow starter switch opensits contacts said voltage source acts at both cathodes of said firstlamp to light the same and thereafter the same remains lit together withsaid second lamp.

2. A system as set forth in claim 1, in which said first impedanceelement comprises a high impedance.

3. A system as set forth in claim 1, in which said second impedanceelement comprises a capacitor shunted by a high resistance.

4. A system as set forth in claim 1, in which said glow starter switchesare each shunted by a small capacitor.

5. A system as set forth in claim 1, in which should said first glowstarter switch open its contacts first, then said contacts of saidsecond glow starter switch open next, thereby reversing the sequence ofthe lighting of said lamps.

6. A system as set forth in claim I, in which said fluorescent lampshave non-filamentary cathodes, whereby said first glow starter switchmay be omitted.

7. In a system of the character described, a first discharge device; asecond discharge device; each of said devices having filamentarycathodes; a first glow starter switch connected in parallel with saidfirst device; a second glow starter switch connected in parallel withsaid second device; a first impedance element; said first impedancebeing connected in parallel with said first device, and beingconnectable in series with said second glow starter switch; a secondimpedance element; a transformer winding; means for energizing saidtransformer winding; a series circuit which includes said transformerwinding, said second impedance element and said first and seconddevices; said first impedance element being of sufficient magnitude suchthat when said transformer winding is initially energized said firstimpedance element prevents a discharge from appearing in said seconddevice and causes a glow discharge to appear in said second glow starterswitch which incorporates whereby the heat produced by said glowdischarge therein causes said switch to close and thereby effectivelytransfer the voltage induced in said transformer winding to said firstglow starter switch to produce a glow discharge therein and to closesaid switch; when both said second and first glow starter switches closetheir contacts preheating current flows through cathode filaments ofsaid devices thereof; as one of said glow starter switches opens itscontacts therein first, said induced voltage acts on both cathodes ofsaid device to which said glow starter switch is connected to light itinstantaneously; and as the other glow starter switch opens its contactpoint the-rein next, said induced voltage acts on both cathodes of saiddevice to which said other glow starter switch is connected to light it.

8. In a system of the character described, a first discharge device; asecond discharge device; each of said devices having non-filamentarycathodes; a first impedance element; a glow starter switch; said firstimpedance element being connected in parallel with first device; saidglow starter switch being connected in parallel with said second device;said glow starter switch being a normally open switch and incorporatingmeans whereby heat from a glow discharge in said glow starter switchcauses said switch to close; said first device being connected in serieswith second device, said first impedance element being connectable inseries with said glow starter switch; a second impedance element; atransformer winding; means for energizing said transformer winding; aseries circuit which includes said transformer winding, said secondimpedance element and said first and second devices; said firstimpedance element being of sutficient magnitude such that when saidtransformer winding is initially energized said first impedance elementprevents a discharge from appearing in said second discharge device andcauses a glow discharge to appear in said glow starter switch whichincorporates means whereby the heat produced by said glow dischargetherein causes said switch to close and thereby efiectively transfer thevoltage induced in said 15 transformer winding to said first device tocause it to start; when said glow starter switch opens its contact pointbeing cooled due to disappearance of said glow discharge, the inducedvoltage acts on both cathodes of said second device to cause it to startnext.

References Cited by the Examiner UNITED STATES PATENTS 2,300,963 11/1942Prescott 315100 2,363,868 11/1944 Karash 315--10O 2,518,767 8/1950Freeman 315-97 2,680,211 6/1954 Campbell 315-189 3,038,103 6/1962 Grecu315-100 3,155,875 11/1964 Wenrich 315100 JAMES W. LAWRENCE, PrimaryExaminer.

GEORGE W. WESTBY, S. D. SCHLOSSER,

Assistant Examiners.

1. IN A FLUORESCENT LAMP CIRCUIT ARRANGEMENT, A FIRST FLUORESCENT LAMP;A SECOND FLUORESCENT LAMP; EACH OF SAID LAMPS HAVING FILAMENTARYCATHODES; MEANS FOR HEATING SAID CATHODE FILAMENTS; A FIRST GLOW STARTERSWITCH; A SECOND GLOW STARTER SWITCH; SAID FIRST GLOW STARTER SWITCHBEING CONNECTED IN PARALLEL WITH SAID FIRST LAMP; SAID SECOND GLOWSTARTER SWITCH BEING CONNECTED IN PARALLEL WITH SAID SECOND LAMP; SAIDGLOW STARTER SWITCHES BEING A NORMALLY OPEN SWITCH AND INCORPORATINGMEANS WHEREBY HEAT FROM A GLOW DISCHARGE IN SAID GLOW STARTER SWITCHCAUSES SAID SWITCHES TO CLOSE; A FIRST IMPEDANCE ELEMENT CONNECTED INPARALLEL WITH SAID FIRST LAMP; SAID FIRST LAMP BEING CONNECTED IN SERIESWITH SAID SECOND LAMP; SAID FIRST GLOW STARTER SWITCH BEING CONNECTED INSERIES WITH SAID SECOND GLOW STARTER SWITCH; SAID FIRST IMPEDANCEELEMENT BEING CONNECTED IN SERIES WITH SAID SECOND GLOW STARTER SWITCH;A VOLTAGE SOURCE; MEANS FOR ENERGIZING SAID VOLTAGE SOURCE; A SECONDIMPEDANCE; SAID VOLTAGE SOURCE, SAID SECOND IMPEDANCE ELEMENT AND SAIDFIRST AND SECOND LAMPS BEING CONNECTED IN SERIES CIRCUIT; SAID FIRSTIMPEDANCE ELE-